/* $Id: mpglib_interface.c,v 1.19 2001/06/11 16:35:18 markt Exp $ */

#define HAVE_MPGLIB
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif


#ifdef HAVE_MPGLIB

#include <limits.h>
#include <stdlib.h>
#include <assert.h>

#include "interface.h"
#include "lame.h"

#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif


MPSTR   mp;
plotting_data *mpg123_pinfo = NULL;


int
lame_decode_init(void)
{
    InitMP3(&mp);
    return 0;
}

/*
 * For lame_decode:  return code
 * -1     error
 *  0     ok, but need more data before outputing any samples
 *  n     number of samples output.  either 576 or 1152 depending on MP3 file.
 */

int
lame_decode1_headers(unsigned char *buffer,
                     int len,
                     short pcm_l[], short pcm_r[], mp3data_struct * mp3data)
{
    static const int smpls[2][4] = {
        /* Layer   I    II   III */
        {0, 384, 1152, 1152}, /* MPEG-1     */
        {0, 384, 1152, 576} /* MPEG-2(.5) */
    };
    static char out[8192];
    signed short int *p = (signed short int *) out;
    int     processed_bytes;
    int     processed_samples; // processed samples per channel
    int     ret;
    int     i;

    mp3data->header_parsed = 0;

    ret =
        decodeMP3(&mp, buffer, len, (char *) p, sizeof(out), &processed_bytes);
    /* three cases:  
     * 1. headers parsed, but data not complete
     *       mp.header_parsed==1 
     *       mp.framesize=0           
     *       mp.fsizeold=size of last frame, or 0 if this is first frame
     *
     * 2. headers, data parsed, but ancillary data not complete
     *       mp.header_parsed==1 
     *       mp.framesize=size of frame           
     *       mp.fsizeold=size of last frame, or 0 if this is first frame
     *
     * 3. frame fully decoded:  
     *       mp.header_parsed==0 
     *       mp.framesize=0           
     *       mp.fsizeold=size of frame (which is now the last frame)
     *
     */
    if (mp.header_parsed || mp.fsizeold > 0 || mp.framesize > 0) {
	mp3data->header_parsed = 1;
        mp3data->stereo = mp.fr.stereo;
        mp3data->samplerate = freqs[mp.fr.sampling_frequency];
        mp3data->mode = mp.fr.mode;
        mp3data->mode_ext = mp.fr.mode_ext;
        mp3data->framesize = smpls[mp.fr.lsf][mp.fr.lay];

	/* free format, we need the entire frame before we can determine
	 * the bitrate.  If we haven't gotten the entire frame, bitrate=0 */
        if (mp.fsizeold > 0) /* works for free format and fixed, no overrun, temporal results are < 400.e6 */
            mp3data->bitrate = 8 * (4 + mp.fsizeold) * mp3data->samplerate /
                (1.e3 * mp3data->framesize) + 0.5;
        else if (mp.framesize > 0)
            mp3data->bitrate = 8 * (4 + mp.framesize) * mp3data->samplerate /
                (1.e3 * mp3data->framesize) + 0.5;
        else
            mp3data->bitrate =
                tabsel_123[mp.fr.lsf][mp.fr.lay - 1][mp.fr.bitrate_index];



        if (mp.num_frames > 0) {
            /* Xing VBR header found and num_frames was set */
            mp3data->totalframes = mp.num_frames;
            mp3data->nsamp = mp3data->framesize * mp.num_frames;
        }
    }

    switch (ret) {
    case MP3_OK:
        switch (mp.fr.stereo) {
        case 1:
            processed_samples = processed_bytes >> 1;
            for (i = 0; i < processed_samples; i++)
                pcm_l[i] = *p++;
            break;
        case 2:
            processed_samples = processed_bytes >> 2;
            for (i = 0; i < processed_samples; i++) {
                pcm_l[i] = *p++;
                pcm_r[i] = *p++;
            }
            break;
        default:
            processed_samples = -1;
            assert(0);
            break;
        }
        break;

    case MP3_NEED_MORE:
        processed_samples = 0;
        break;

    default:
        assert(0);
    case MP3_ERR:
        processed_samples = -1;
        break;

    }

    //fprintf(stderr,"ok, more, err:  %i %i %i\n", MP3_OK, MP3_NEED_MORE, MP3_ERR );
    //fprintf(stderr,"ret = %i out=%i\n", ret, processed_samples );
    return processed_samples;
}


/*
 * For lame_decode:  return code
 *  -1     error
 *   0     ok, but need more data before outputing any samples
 *   n     number of samples output.  Will be at most one frame of
 *         MPEG data.  
 */

int
lame_decode1(unsigned char *buffer, int len, short pcm_l[], short pcm_r[])
{
    mp3data_struct mp3data;

    return lame_decode1_headers(buffer, len, pcm_l, pcm_r, &mp3data);
}


/*
 * For lame_decode:  return code
 *  -1     error
 *   0     ok, but need more data before outputing any samples
 *   n     number of samples output.  a multiple of 576 or 1152 depending on MP3 file.
 */

int
lame_decode_headers(unsigned char *buffer,
                    int len,
                    short pcm_l[], short pcm_r[], mp3data_struct * mp3data)
{
    int     ret;
    int     totsize = 0;     // number of decoded samples per channel

    while (1) {
        switch (ret =
                lame_decode1_headers(buffer, len, pcm_l + totsize,
                                     pcm_r + totsize, mp3data)) {
        case -1:
            return ret;
        case 0:
            return totsize;
        default:
            totsize += ret;
            len = 0;    /* future calls to decodeMP3 are just to flush buffers */
            break;
        }
    }
}


int
lame_decode(unsigned char *buffer, int len, short pcm_l[], short pcm_r[])
{
    mp3data_struct mp3data;

    return lame_decode_headers(buffer, len, pcm_l, pcm_r, &mp3data);
}


#endif

/* end of mpglib_interface.c */
